This invention relates to a method and device for raising and lowering blinds of the pleated type, roll-up type, or drapery-fabric Roman type, and more particularly to an endless roll-up mechanism for a blind of the pleated type, roll-up type, or drapery-fabric Roman type.
In blinds of the roll-up type, the pleated type or the drapery-fabric Roman type, it is difficult to precisely roll and unroll these blinds. For simplicity, reference to one member of the class of blinds includes all members of the class unless otherwise specified.
Blinds of the roll-up type generally have small slats strung together with a rolling type mechanism associated therewith. While bamboo is a common material used in blinds of the roll-up type, it is quite feasible to replace bamboo with wood or synthetic plastic slats of flat or tubular form. Roll-up is used herein as a standard definition of this type of blind. Basically, blinds of the roll-up type have a plurality of slats woven together, which can be rolled and unrolled.
A pleated blind, on the other hand, folds up along predetermined fold lines in fabric or other suitable material. The material used to form the pleated blind is stiffened in a known fashion to encourage folding along those predetermined lines.
The drapery-fabric Roman type blind incorporates a pull cord fixed to a bottom portion of the blind with the pull cord passing thorough a series of loops vertically secured to the fabric at spaced intervals. This structure causes the fabric to bend or fold between each pair of the loops as the blind is pulled up.
There is great difficulty involved in getting blinds to pull or roll-up evenly. Multiple pull or roll lines or cords (usually from two to six) pull or roll-up or let down these pleated or roll-up type blinds. Thus, the blinds are such that one side or the other can advance too much and roll or pull the one side higher than the other, creating a very uneven, non-aesthetic blind elevation.
When there are four (4) roll-up cords, as opposed to two roll-up cords, the problem is compounded. Each of the four cords can tangle or come off its respective rolling mechanism and throw the blind substantially off in its take up (roll-up) or let down. Thus, more roll-up cords provide more difficulty in a uniform rolling of the blind.
The device for rolling these blinds up and down is complex and difficult to operate because a great amount of cord is necessary to achieve the desired rolling up effect. For instance, an activating cord is provided which operates and coordinates the multiple roll cords. Thus, when the blind is rolled up, there is a substantial amount of activating cord exposed which is cumbersome to store.
When the blind is rolled up, the activating cord dangles to the floor, and becomes an unsightly nuisance as well as a danger to the safety of small children. In fact, the U.S. Consumer Product Safety Commission based in Washington, D.C., is the author of a Consumer Product Safety Alert regarding window blind or drapery cords, stating that a small child can be strangled by such exposed, dangling cord. The Commission recommends tying up or clamping the cord out of a child's reach. This tying up or clamping is cumbersome and interferes with the rapid use and aesthetic appearance of the blind.
It has also proven difficult to provide a holding mechanism to maintain the position the rolling mechanism appropriately. By positioning the rolling mechanism appropriately, the desired blind roll-up level can be obtained while at the same time preventing unscheduled rolldowns of the blind.
Thus, many complicating structures are necessary to achieve the desired roll-up characteristics in a blind. If the structure to achieve the desired even roll-up can be simplified, great advantages are obtained.